The present invention relates generally to infrared spectroscopy and mass spectrometry, and, more specifically, to pyrolysis of polymer specimens for analysis therein.
In order to effectively recycle plastic or polymeric parts such as engineering thermoplastics found in an automobile, the type of polymer must be identified in order to segregate parts made from the same material. In an industrial recycling plant, the different plastic parts must be properly identified and segregated for cost efficiency. Segregation of the parts may be accomplished by visual identification where possible, and where not possible, the parts must be suitably analyzed to determine the chemical composition thereof.
Pyrolysis of polymers or plastics followed by conventional spectrochemical analysis is one conventional approach for determining chemical composition of an analyzed specimen. In pyrolysis, a specimen in the form of a small sample is suitably heated in an air environment for obtaining chemical decomposition thereof and the release of pyrolysis products which are volatile heated vapors also referred to as pyrolysate. The pyrolysate is then carried by the air to an infrared spectrometer for the conventional chemical analysis thereof. The pyrolysate may also be analyzed in a conventional mass spectrometer to determine the chemical composition. However mass spectrometers typically require an inert gas such as helium for transporting the pyrolysate therein, in which case a conventional separator membrane is typically used to transfer the pyrolysate from the heated air through the membrane to the helium on the other side thereof. An exemplary membrane includes a layer of silicone sandwiched between two stainless steel wire meshes in a flat disk form which can be suitably mounted in a housing.
In view of the complexity of the conventional equipment used in pyrolysis and infrared or mass spectrometry, the use thereof in a high speed, high volume plastics recycling plant is not practical.